Rubber compound



UNITED STATES PATENT OFFICE.

N. CHAPMAN MITCHELL, OF PHILADELPHIA, PENNSYLVANIA.

RUBBER COMPOUND.

SPZCIFIC'ATION forming part of Letters Patent No. 290,909, dated. December 25, 183?.

Application filed November 5, 1883. (No specimens.)

To all whom it may concern..-

Beit known that I, N. CHAPMAN MITCHELL, a citizen of the United States, and a resident of Philadelphia, Pennsylvania, have invented an Improvement in Rubber Compounds, of which the following is a specification.

The object of my invention is to improve the wearing qualities and cheapen the manufacture of rubber compoundssuch, for instance, as are used for the soles and heels of boots and shoes; and this object I attain by combining leather with the compound prior to its vulcanization.

In carrying out my invention I first reduce the leather preferably to a powder, either coarse or fine, as may be desired, by grinding or in any other suitable manner, and this divided leather I add to the raw rubber along with the sulphur, whiting, and other materials with which the rubber is usually mixed prior to its vulcanization.

The proportion of leather may be varied as the uses to which the compound is to be put may suggest. The addition of the leather serves to materially improvethe wearing qualities of the compound, and to prevent its surface from becoming smooth, thus overcoming two serious objections to compounds now used.

Scrap-leather is preferably used on the score of economy, it being cheaper than most of the materials now compounded with rubber.

The leather, being in a divided state'and distributed throughout the compound, is in the best condition for effecting the object for which it is employed.

I claim as my invention 1. The mode herein described of improving the quality of rubber compounds, said mode consisting in mixing particles of leather k with the compound previous to vulcanization, as set forth.

2. As a new article of manufacture, a rubber compound having particles of leather dis tributed throughout the same, as set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

" N. CHAPMAN MITCHELL.

IVitnesses:

J OHN E. PARKER, HARRY SMITH. 

